4.10. Lamps with asymmetrical "cut-off" line designed to satisfy the requirements both of right hand and of left hand traffic may be adapted for traffic on a given side of the road either by an appropriate initial setting when fitted on the vehicle or by selective setting by the user. Such initial or selective setting may consist, for example, of fixing either the optical unit at a given angle on the vehicle or the light source(s) producing the principal passing-beam at a given angle/position in relation to the optical unit. a0c0